rlm_smtp.c

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/*
 *   This program is is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or (at
 *   your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * $Id: c29d039f246b55c2f29abd5e6220f2b7f02c3d6f $
 * @file rlm_smtp.c
 * @brief smtp server authentication.
 *
 * @copyright 2020 The FreeRADIUS server project
 * @copyright 2020 Network RADIUS SAS (legal@networkradius.com)
 */
RCSID("$Id: c29d039f246b55c2f29abd5e6220f2b7f02c3d6f $")
 
#include <freeradius-devel/curl/base.h>
#include <freeradius-devel/server/base.h>
#include <freeradius-devel/server/cf_priv.h>
#include <freeradius-devel/server/global_lib.h>
#include <freeradius-devel/server/module_rlm.h>
#include <freeradius-devel/server/tmpl_dcursor.h>
#include <freeradius-devel/util/slab.h>
#include <freeradius-devel/util/token.h>
 
#include <freeradius-devel/unlang/call_env.h>
 
static fr_dict_t const  *dict_freeradius;
 
extern fr_dict_autoload_t rlm_smtp_dict[];
fr_dict_autoload_t rlm_smtp_dict[] = {
        { .out = &dict_freeradius, .proto = "freeradius"},
        { NULL }
};
 
static fr_dict_attr_t const     *attr_smtp_header;
static fr_dict_attr_t const     *attr_smtp_body;
 
extern fr_dict_attr_autoload_t rlm_smtp_dict_attr[];
fr_dict_attr_autoload_t rlm_smtp_dict_attr[] = {
        { .out = &attr_smtp_header, .name = "SMTP-Mail-Header", .type = FR_TYPE_STRING, .dict = &dict_freeradius },
        { .out = &attr_smtp_body, .name = "SMTP-Mail-Body", .type = FR_TYPE_STRING, .dict = &dict_freeradius },
        { NULL },
};
 
extern global_lib_autoinst_t const * const rlm_smtp_lib[];
global_lib_autoinst_t const * const rlm_smtp_lib[] = {
        &fr_curl_autoinst,
        GLOBAL_LIB_TERMINATOR
};
 
/** Call environment for sending emails.
*/
typedef struct {
        fr_value_box_t          username;               //!< User to authenticate as when sending emails.
        tmpl_t                  *username_tmpl;         //!< The tmpl used to produce the above.
        fr_value_box_t          password;               //!< Password for authenticated mails.
        fr_value_box_list_t     *sender_address;        //!< The address(es) used to generate the From: header
        fr_value_box_list_t     *recipient_addrs;       //!< The address(es) used as recipients.  Overrides elements in to, cc and bcc
        fr_value_box_list_t     *to_addrs;              //!< The address(es) used for the To: header.
        fr_value_box_list_t     *cc_addrs;              //!< The address(es) used for the Cc: header.
        fr_value_box_list_t     *bcc_addrs;             //!< The address(es) used for the Bcc: header.
        fr_value_box_list_t     *attachments;           //!< List of files to attach.
        fr_value_box_list_t     headers;                //!< Entries to add to email header.
} rlm_smtp_env_t;
 
/** Call environment for SMTP authentication
 */
typedef struct {
        fr_value_box_t          username;               //!< Value to use for user name
        tmpl_t                  *username_tmpl;         //!< tmpl expanded to populate username
        fr_value_box_t          password;               //!< Value to use for password
        tmpl_t                  *password_tmpl;         //!< tmpl expanded to populate password
} rlm_smtp_auth_env_t;
 
typedef struct {
        char const              *uri;                   //!< URI of smtp server
        char const              *template_dir;          //!< The directory that contains all email attachments
        char const              *envelope_address;      //!< The address used to send the message
 
        fr_time_delta_t         timeout;                //!< Timeout for connection and server response
        fr_curl_tls_t           tls;                    //!< Used for handled all tls specific curl components
 
        bool                    set_date;
 
        fr_curl_conn_config_t   conn_config;            //!< Reusable CURL handle config
} rlm_smtp_t;
 
/*
 *      A mapping of configuration file names to internal variables.
 */
static const conf_parser_t module_config[] = {
        { FR_CONF_OFFSET("uri", rlm_smtp_t, uri) },
        { FR_CONF_OFFSET("template_directory", rlm_smtp_t, template_dir) },
        { FR_CONF_OFFSET("envelope_address", rlm_smtp_t, envelope_address) },
        { FR_CONF_OFFSET("timeout", rlm_smtp_t, timeout) },
        { FR_CONF_OFFSET("set_date", rlm_smtp_t, set_date), .dflt = "yes" },
        { FR_CONF_OFFSET_SUBSECTION("tls", 0, rlm_smtp_t, tls, fr_curl_tls_config) },//!<loading the tls values
        { FR_CONF_OFFSET_SUBSECTION("connection", 0, rlm_smtp_t, conn_config, fr_curl_conn_config) },
        CONF_PARSER_TERMINATOR
};
 
/*
 *      Two types of SMTP connections are used:
 *       - persistent - where the connection can be left established as the same
 *                      authentication is used for all mails sent.
 *       - onetime    - where the connection is torn down after each use, since
 *                      different authentication is needed each time.
 *
 *      Memory for the handles for each is stored in slabs.
 */
 
FR_SLAB_TYPES(smtp, fr_curl_io_request_t)
FR_SLAB_FUNCS(smtp, fr_curl_io_request_t)
 
typedef struct {
        fr_curl_handle_t        *mhandle;       //!< Thread specific multi handle.  Serves as the dispatch and
                                                ///< coralling structure for smtp requests
        smtp_slab_list_t        *slab_persist;  //!< Slab list for persistent connections.
        smtp_slab_list_t        *slab_onetime;  //!< Slab list for onetime use connections.
} rlm_smtp_thread_t;
 
/*
 *      Holds the context for parsing the email elements
 */
typedef struct {
        request_t               *request;
        fr_curl_io_request_t    *randle;
        fr_dcursor_t            cursor;
        fr_dcursor_t            body_cursor;
        fr_dbuff_t              vp_in;
 
        struct curl_slist       *recipients;
        struct curl_slist       *header;
        struct curl_slist       *body_header;
 
        fr_time_t               time;
        char                    time_str[60];
        curl_mime               *mime;
} fr_mail_ctx_t;
 
/*
 *      Adds every element associated with a dict_attr to a curl_slist
 */
static int da_to_slist(fr_mail_ctx_t *uctx, struct curl_slist **out, const fr_dict_attr_t *dict_attr)
{
        request_t                       *request = ((fr_mail_ctx_t *)uctx)->request;
        fr_pair_t                       *vp;
        int                             elems_added = 0;
 
        /* Iterate over the VP and add the string value to the curl_slist */
        vp = fr_pair_dcursor_by_da_init(&uctx->cursor, &uctx->request->request_pairs, dict_attr);
 
        while (vp) {
                *out = curl_slist_append(*out, vp->vp_strvalue);
                vp = fr_dcursor_next(&uctx->cursor);
                elems_added++;
        }
 
        if (!elems_added) RDEBUG3("There were no %s elements found", dict_attr->name);
 
        return elems_added;
}
 
/** Transform an array of value box lists to entries in a CURL slist
 *
 */
static int value_box_list_to_slist(struct curl_slist **out, fr_value_box_list_t const *lists)
{
        fr_value_box_list_t const       *list = lists;
        fr_value_box_t                  *vb = NULL;
        int                             count = 0;
        size_t                          i, list_count = talloc_array_length(lists);
 
        for (i = 0; i < list_count; i++) {
                while ((vb = fr_value_box_list_next(list, vb))) {
                        *out = curl_slist_append(*out, vb->vb_strvalue);
                        count ++;
                }
                list++;
        }
 
        return count;
}
 
/** Converts an array of value box lists to a curl_slist with a prefix
 *
 * @param uctx          Mail context.
 * @param out           CURL slist to write to.
 * @param lists         Array of value box lists to copy.
 * @param prefix        to prepend to the output slist
 * @return
 *   - 1 on success
 *   - 0 if no slist entry was created
 *   - -1 on failure
 */
static int value_box_list_to_header(fr_mail_ctx_t *uctx, struct curl_slist **out, fr_value_box_list_t const *lists,
                                    const char *prefix)
{
        request_t                       *request = uctx->request;
        fr_sbuff_t                      sbuff;
        fr_sbuff_uctx_talloc_t          sbuff_ctx;
        bool                            added = false;
        fr_value_box_t                  *vb = NULL;
        fr_value_box_list_t const       *list = lists;
        size_t                          i, list_count = talloc_array_length(lists);
 
        fr_sbuff_init_talloc(uctx, &sbuff, &sbuff_ctx, 256, SIZE_MAX);
        (void) fr_sbuff_in_strcpy(&sbuff, prefix);
 
        for (i = 0; i < list_count; i++) {
                while ((vb = fr_value_box_list_next(list, vb))) {
                        /* If there are already values added, add the comma separator */
                        if (added) {
                                if (unlikely(fr_sbuff_in_strcpy(&sbuff, ", ") < 0)) {
                                error:
                                        talloc_free(fr_sbuff_buff(&sbuff));
                                        return -1;
                                }
                        }
 
                        if ((vb->type != FR_TYPE_STRING) && (fr_value_box_cast_in_place(vb, vb, FR_TYPE_STRING, NULL) < 0)) {
                                RERROR("Failed casting %pV to string", vb);
                                goto error;
                        }
 
                        if (unlikely(fr_sbuff_in_strcpy(&sbuff, vb->vb_strvalue) < 0)) goto error;
                        added = true;
                }
                list++;
        }
 
        if (!added) {
                RDEBUG2("No values to add to \"%s\" header", prefix);
                talloc_free(fr_sbuff_buff(&sbuff));
                return 0;
        }
 
        /* Add the generated buffer the the curl_slist */
        *out = curl_slist_append(*out, fr_sbuff_buff(&sbuff));
        talloc_free(fr_sbuff_buff(&sbuff));
        return 1;
}
 
/*
 *      Takes a string value and adds it as a file path to upload as an attachment
 */
static int str_to_attachments(fr_mail_ctx_t *uctx, curl_mime *mime, char const * str, size_t len,
                              fr_sbuff_t *path_buffer, fr_sbuff_marker_t *m)
{
        request_t               *request = uctx->request;
        curl_mimepart           *part;
 
        /* Move to the end of the template directory filepath */
        fr_sbuff_set(path_buffer, m);
 
        /* Check to see if the file attachment is valid, skip it if not */
        RDEBUG2("Trying to set attachment: %s", str);
 
        if (strncmp(str, "/", 1) == 0) {
                RDEBUG2("File attachments cannot be an absolute path");
                return 0;
        }
 
        if (strncmp(str, "..", 2) == 0) {
                RDEBUG2("Cannot access values outside of template_directory");
                return 0;
        }
 
        /* Copy the filename into the buffer */
        if (fr_sbuff_in_bstrncpy(path_buffer, str, len) < 0) {
                RDEBUG2("Cannot copy filename");
                return 0;
        }
 
        /* Add the file attachment as a mime encoded part */
        part = curl_mime_addpart(mime);
        curl_mime_encoder(part, "base64");
        if (curl_mime_filedata(part, path_buffer->buff) != CURLE_OK) {
                REDEBUG2("Cannot add file attachment");
                return 0;
        }
 
        return 1;
}
 
/** Generate the `From:` header
 *
 * Defaults to using `sender_address` values, falls back to `envelope_address`
 */
static int generate_from_header(fr_mail_ctx_t *uctx, struct curl_slist **out, rlm_smtp_t const *inst,
                                rlm_smtp_env_t const *call_env)
{
        fr_sbuff_t                      sbuff;
        fr_sbuff_uctx_talloc_t          sbuff_ctx;
 
        if (call_env->sender_address) return value_box_list_to_header(uctx, &uctx->header, call_env->sender_address, "From: ");
 
        /* Initialize the buffer for the recipients. Used for FROM */
        fr_sbuff_init_talloc(uctx, &sbuff, &sbuff_ctx, 256, SIZE_MAX);
 
        /* Add the preposition for the header element */
        (void) fr_sbuff_in_strcpy(&sbuff, "From: ");
 
        /* Copy the envelope address as the From: source */
        if (unlikely(fr_sbuff_in_bstrncpy(&sbuff, inst->envelope_address,
                                          strlen(inst->envelope_address)) < 0)) {
                talloc_free(fr_sbuff_buff(&sbuff));
                return -1;
        }
 
        *out = curl_slist_append(*out, sbuff.buff);
 
        /* Free the buffer used to generate the FROM header */
        talloc_free(fr_sbuff_buff(&sbuff));
 
        return 0;
}
 
/*
 *      Generates a curl_slist of recipients
 */
static int recipients_source(fr_mail_ctx_t *uctx, rlm_smtp_env_t const *call_env)
{
        request_t       *request = uctx->request;
        int             recipients_set = 0;
 
        /*
          *     Try to load the recipients into the envelope recipients if they are set
          */
        if(call_env->recipient_addrs) {
                recipients_set += value_box_list_to_slist(&uctx->recipients, call_env->recipient_addrs);
        }
 
        /*
         *      If any recipients were found, ignore to cc and bcc, return the amount added.
         **/
        if (recipients_set) {
                RDEBUG2("Recipients were generated from \"&SMTP-Recipients\" and/or recipients in the config");
                return recipients_set;
        }
        RDEBUG2("No addresses were found in \"&SMTP-Recipients\"");
 
        /*
         *      Try to load the to: addresses into the envelope recipients if they are set
         */
        if (call_env->to_addrs) recipients_set += value_box_list_to_slist(&uctx->recipients, call_env->to_addrs);
 
        /*
         *      Try to load the cc: addresses into the envelope recipients if they are set
         */
        if (call_env->cc_addrs) recipients_set += value_box_list_to_slist(&uctx->recipients, call_env->cc_addrs);
 
        /*
         *      Try to load the bcc: addresses into the envelope recipients if they are set
         */
        if (call_env->bcc_addrs) recipients_set += value_box_list_to_slist(&uctx->recipients, call_env->bcc_addrs);
 
        RDEBUG2("%d recipients set", recipients_set);
        return recipients_set;
}
 
/*
 *      Generates a curl_slist of header elements header elements
 */
static int header_source(fr_mail_ctx_t *uctx, rlm_smtp_t const *inst, rlm_smtp_env_t const *call_env)
{
        fr_sbuff_t                      time_out;
        request_t                       *request = uctx->request;
        fr_value_box_t                  *vb = NULL;
 
        /*
         *      Load in all of the header elements supplied in the config
         */
        if (fr_value_box_list_initialised(&call_env->headers)) {
                while ((vb = fr_value_box_list_next(&call_env->headers, vb))) {
                        RDEBUG2("Adding header \"%pV\"", vb);
                        uctx->header = curl_slist_append(uctx->header, vb->vb_strvalue);
                }
        }
 
        /* Add the From: line */
        if (unlikely(generate_from_header(uctx, &uctx->header, inst, call_env) < 0)) {
                RDEBUG2("From: header could not be added");
                return -1;
        }
 
        /* Add the TO: line if there is one provided in the request by SMTP-TO */
        value_box_list_to_header(uctx, &uctx->header, call_env->to_addrs, "To: ");
 
        /* Add the CC: line if there is one provided in the request by SMTP-CC */
        value_box_list_to_header(uctx, &uctx->header, call_env->cc_addrs, "Cc: ");
 
        /* Add all the generic header elements in the request */
        da_to_slist(uctx, &uctx->header, attr_smtp_header);
 
        /* If no header elements could be found, there is an error */
        if (!uctx->header) {
                RDEBUG2("Header elements could not be added");
                return -1;
        }
 
        /* Set the DATE: to the time that the request was received */
        if (inst->set_date) {
                time_out = FR_SBUFF_OUT(uctx->time_str, sizeof(uctx->time_str));
                fr_time_strftime_local(&time_out, fr_time(), "DATE: %a, %d %b %Y %T %z, (%Z) \r\n");
                uctx->header = curl_slist_append(uctx->header, uctx->time_str);
        }
 
        RDEBUG2("Finished generating the curl_slist for the header elements");
        return 0;
}
 
/*
 *      Add the Body elements to the email
 */
static size_t body_source(char *ptr, size_t size, size_t nmemb, void *mail_ctx)
{
        fr_mail_ctx_t           *uctx = mail_ctx;
        fr_dbuff_t              out;
        request_t               *request = uctx->request;
        fr_pair_t               *vp;
 
        fr_dbuff_init(&out, (uint8_t *)ptr, (size * nmemb));  /* Wrap the output buffer so we can track our position easily */
 
        vp = fr_dcursor_current(&uctx->body_cursor);
        if (!vp) {
                RDEBUG2("vp could not be found for the body element");
                return 0;
        }
 
        /*
         *      Copy the vp into the email. If it cannot all be
         *      loaded, return the amount of memory that was loaded
         *      and get called again.
         */
        if (fr_dbuff_in_memcpy_partial(&out, &uctx->vp_in, SIZE_MAX) < fr_dbuff_remaining(&uctx->vp_in)) {
                RDEBUG2("%zu bytes used (partial copy)", fr_dbuff_used(&out));
                return fr_dbuff_used(&out);
        }
 
        /*
         *      Once this value pair is fully copied, prepare for the next element
         */
        vp = fr_dcursor_next(&uctx->body_cursor);
        if (vp) {
                fr_dbuff_init(&uctx->vp_in, (uint8_t const *)vp->vp_strvalue, vp->vp_length);
 
        }
 
        RDEBUG2("%zu bytes used (full copy)", fr_dbuff_used(&out));
        return fr_dbuff_used(&out);
}
 
/*
 *      Initialize all the body elements to be uploaded later
 */
static int body_init(fr_mail_ctx_t *uctx, curl_mime *mime)
{
        fr_pair_t       *vp;
        request_t       *request = uctx->request;
 
        curl_mimepart   *part;
        curl_mime       *mime_body;
 
        int             body_elements = 0;
 
        /* Initialize a second mime to apply special conditions to the body elements */
        MEM(mime_body = curl_mime_init(uctx->randle->candle));
 
        /* initialize the cursor used by the body_source function*/
        vp = fr_pair_dcursor_by_da_init(&uctx->body_cursor, &uctx->request->request_pairs, attr_smtp_body);
        fr_dbuff_init(&uctx->vp_in, (uint8_t const *)vp->vp_strvalue, vp->vp_length);
 
        /* Add a mime part to mime_body for every body element */
        while (vp) {
                body_elements++;
                MEM(part = curl_mime_addpart(mime_body));
 
                curl_mime_encoder(part, "8bit");
                curl_mime_data_cb(part, vp->vp_length, body_source, NULL, NULL, uctx);
 
                vp = fr_dcursor_next(&uctx->body_cursor);
        }
        RDEBUG2("initialized %d body element part(s)", body_elements);
 
        /* Re-initialize the cursor for use when uploading the data to curl */
        fr_pair_dcursor_by_da_init(&uctx->body_cursor, &uctx->request->request_pairs, attr_smtp_body);
 
        /*
         *      Add body_mime as a subpart of the mime request with a local content-disposition
         */
        MEM(part = curl_mime_addpart(mime));
        curl_mime_subparts(part, mime_body);
        MEM(curl_mime_type(part, "multipart/mixed") == CURLE_OK);
        uctx->body_header = curl_slist_append(NULL, "Content-Disposition: inline"); /* Initialize the body_header curl_slist */
        curl_mime_headers(part, uctx->body_header, 1);
 
        return body_elements;
}
 
/*
 *      Adds every SMTP_Attachments file to the email as a MIME part
 */
static int attachments_source(fr_mail_ctx_t *uctx, curl_mime *mime, rlm_smtp_t const *inst, rlm_smtp_env_t const *call_env)
{
        request_t                       *request = uctx->request;
        int                             attachments_set = 0;
        fr_sbuff_uctx_talloc_t          sbuff_ctx;
        fr_sbuff_t                      path_buffer;
        fr_sbuff_marker_t               m;
        fr_value_box_t                  *vb = NULL;
        fr_value_box_list_t const       *list = call_env->attachments;
        size_t                          i, list_count = talloc_array_length(call_env->attachments);
 
 
        /* Make sure that a template directory is provided */
        if (!inst->template_dir) return 0;
 
        /* Initialize the buffer to write the file path */
        fr_sbuff_init_talloc(uctx, &path_buffer, &sbuff_ctx, talloc_array_length(inst->template_dir) + 128, SIZE_MAX);
 
        /* Write the initial path to the buffer */
        fr_sbuff_in_bstrcpy_buffer(&path_buffer, inst->template_dir);
 
        /* Make sure the template_directory path ends in a "/" */
        if (inst->template_dir[talloc_array_length(inst->template_dir)-2] != '/'){
                RDEBUG2("Adding / to end of template_dir");
                (void) fr_sbuff_in_char(&path_buffer, '/');
        }
 
        /* Mark the buffer so we only re-write after the template_dir component */
        fr_sbuff_marker(&m, &path_buffer);
 
        /* Add the attachments to the email */
        for (i = 0; i < list_count; i++) {
                while ((vb = fr_value_box_list_next(list, vb))) {
                        attachments_set += str_to_attachments(uctx, mime, vb->vb_strvalue, vb->vb_length, &path_buffer, &m);
                }
                list++;
        }
 
        /* Check for any file attachments */
        talloc_free(path_buffer.buff);
        return attachments_set;
}
 
static void smtp_io_module_signal(module_ctx_t const *mctx, request_t *request, UNUSED fr_signal_t action)
{
        fr_curl_io_request_t    *randle = talloc_get_type_abort(mctx->rctx, fr_curl_io_request_t);
        rlm_smtp_thread_t       *t = talloc_get_type_abort(mctx->thread, rlm_smtp_thread_t);
        CURLMcode               ret;
 
        RDEBUG2("Forcefully cancelling pending SMTP request");
 
        ret = curl_multi_remove_handle(t->mhandle->mandle, randle->candle);     /* Gracefully terminate the request */
        if (ret != CURLM_OK) {
                RERROR("Failed removing curl handle from multi-handle: %s (%i)", curl_multi_strerror(ret), ret);
                /* Not much we can do */
        }
        t->mhandle->transfers--;
        smtp_slab_release(randle);
}
 
/**     Callback to process response of SMTP server
 *
 *      It checks if the response was CURLE_OK
 *      If it was, it tries to extract the certificate attributes
 *      If the response was not OK, we REJECT the request
 *      When responding to requests initiated by mod_authenticate this is simply
 *      a check on the username and password.
 *      When responding to requests initiated by mod_mail this indicates
 *      the mail has been queued.
 */
static unlang_action_t smtp_io_module_resume(rlm_rcode_t *p_result, module_ctx_t const *mctx, request_t *request)
{
        rlm_smtp_t const                *inst = talloc_get_type_abort_const(mctx->mi->data, rlm_smtp_t);
        fr_curl_io_request_t            *randle = talloc_get_type_abort(mctx->rctx, fr_curl_io_request_t);
        fr_curl_tls_t const             *tls = &inst->tls;
        long                            curl_out;
        long                            curl_out_valid;
 
        curl_out_valid = curl_easy_getinfo(randle->candle, CURLINFO_SSL_VERIFYRESULT, &curl_out);
        if (curl_out_valid == CURLE_OK){
                RDEBUG2("server certificate %s verified", curl_out ? "was" : "not");
        } else {
                RDEBUG2("server certificate result not found");
        }
 
        if (randle->result != CURLE_OK) {
                CURLcode result = randle->result;
                smtp_slab_release(randle);
                switch (result) {
                case CURLE_PEER_FAILED_VERIFICATION:
                case CURLE_LOGIN_DENIED:
                        RETURN_MODULE_REJECT;
                default:
                        RETURN_MODULE_FAIL;
                }
        }
 
        if (tls->extract_cert_attrs) fr_curl_response_certinfo(request, randle);
        smtp_slab_release(randle);
 
        RETURN_MODULE_OK;
}
 
/*
 *      Checks that there is a User-Name and User-Password field in the request
 *      As well as all of the required SMTP elements
 *      Sets the: username, password
 *              website URI
 *              timeout information
 *              TLS information
 *              Sender and recipient information
 *              Email header and body
 *              File attachments
 *
 *      Then it queues the request and yields until a response is given
 *      When it responds, smtp_io_module_resume is called.
 */
static unlang_action_t CC_HINT(nonnull) mod_mail(rlm_rcode_t *p_result, module_ctx_t const *mctx, request_t *request)
{
        rlm_smtp_t const                *inst = talloc_get_type_abort_const(mctx->mi->data, rlm_smtp_t);
        rlm_smtp_thread_t               *t = talloc_get_type_abort(mctx->thread, rlm_smtp_thread_t);
        rlm_smtp_env_t                  *call_env = talloc_get_type_abort(mctx->env_data, rlm_smtp_env_t);
        fr_curl_io_request_t            *randle = NULL;
        fr_mail_ctx_t                   *mail_ctx;
 
        fr_pair_t const                 *smtp_body;
 
        /* Elements provided by the request */
        smtp_body = fr_pair_find_by_da(&request->request_pairs, NULL, attr_smtp_body);
 
        /* Make sure all of the essential email components are present and possible*/
        if (!smtp_body) {
                RDEBUG2("Attribute \"smtp-body\" is required for smtp");
                RETURN_MODULE_INVALID;
        }
 
        if (!call_env->sender_address && !inst->envelope_address) {
                RDEBUG2("At least one of \"sender_address\" or \"envelope_address\" in the config, or \"SMTP-Sender-Address\" in the request is needed");
        error:
                if (randle) smtp_slab_release(randle);
                RETURN_MODULE_INVALID;
        }
 
        /*
         *      If the username is defined and is not static data
         *      a onetime connection is used, otherwise a persistent one
         *      can be used.
         */
        randle = (call_env->username_tmpl &&
                  !tmpl_is_data(call_env->username_tmpl)) ? smtp_slab_reserve(t->slab_onetime) :
                                                            smtp_slab_reserve(t->slab_persist);
        if (!randle) {
                RDEBUG2("A handle could not be allocated for the request");
                RETURN_MODULE_FAIL;
        }
 
        /* Initialize the uctx to perform the email */
        mail_ctx = talloc_get_type_abort(randle->uctx, fr_mail_ctx_t);
        *mail_ctx = (fr_mail_ctx_t) {
                .request        = request,
                .randle         = randle,
                .mime           = curl_mime_init(randle->candle),
                .time           = fr_time(), /* time the request was received. Used to set DATE: */
                .recipients     = NULL,
                .header         = NULL
        };
 
        FR_CURL_REQUEST_SET_OPTION(CURLOPT_UPLOAD, 1L);
 
        /* Set the username and password if they have been provided */
        if (call_env->username.vb_strvalue) {
                FR_CURL_REQUEST_SET_OPTION(CURLOPT_USERNAME, call_env->username.vb_strvalue);
 
                if (!call_env->password.vb_strvalue) goto skip_auth;
 
                FR_CURL_REQUEST_SET_OPTION(CURLOPT_PASSWORD, call_env->password.vb_strvalue);
                RDEBUG2("Username and password set");
        }
 
skip_auth:
        /* Set the envelope mail from address */
        FR_CURL_REQUEST_SET_OPTION(CURLOPT_MAIL_FROM,
                                   (inst->envelope_address ? inst->envelope_address :
                                    fr_value_box_list_head(call_env->sender_address)->vb_strvalue));
 
        /* Set the recipients */
        if (recipients_source(mail_ctx, call_env) <= 0) {
                REDEBUG("At least one recipient is required to send an email");
                goto error;
        }
        FR_CURL_REQUEST_SET_OPTION(CURLOPT_MAIL_RCPT, mail_ctx->recipients);
 
        /* Set the header elements */
        if (header_source(mail_ctx, inst, call_env) != 0) {
                REDEBUG("The header slist could not be generated");
                goto error;
        }
 
        /*
         *      CURLOPT_HTTPHEADER is the option that they use for the header in the curl example
         *
         *      https://curl.haxx.se/libcurl/c/smtp-mime.html
         */
        FR_CURL_REQUEST_SET_OPTION(CURLOPT_HTTPHEADER, mail_ctx->header);
 
        /* Initialize the body elements to be uploaded */
        if (body_init(mail_ctx, mail_ctx->mime) == 0) {
                REDEBUG("The body could not be generated");
                goto error;
        }
 
        /* Initialize the attachments if there are any*/
        if (attachments_source(mail_ctx, mail_ctx->mime, inst, call_env) == 0){
                RDEBUG2("No files were attached to the email");
        }
 
        /* Add the mime endoced elements to the curl request */
        FR_CURL_REQUEST_SET_OPTION(CURLOPT_MIMEPOST, mail_ctx->mime);
 
        if (fr_curl_io_request_enqueue(t->mhandle, request, randle)) RETURN_MODULE_INVALID;
 
        return unlang_module_yield(request, smtp_io_module_resume, smtp_io_module_signal, ~FR_SIGNAL_CANCEL, randle);
}
 
/*
 *      Sets the: username, password
 *              website URI
 *              timeout information
 *              and TLS information
 *
 *      Then it queues the request and yields until a response is given
 *      When it responds, smtp_io_module_resume is called.
 */
static unlang_action_t CC_HINT(nonnull(1,2)) mod_authenticate(rlm_rcode_t *p_result, module_ctx_t const *mctx, request_t *request)
{
        rlm_smtp_thread_t       *t = talloc_get_type_abort(mctx->thread, rlm_smtp_thread_t);
        rlm_smtp_auth_env_t     *env_data = talloc_get_type_abort(mctx->env_data, rlm_smtp_auth_env_t);
        fr_curl_io_request_t    *randle;
 
        randle = smtp_slab_reserve(t->slab_onetime);
        if (!randle) RETURN_MODULE_FAIL;
 
        if (env_data->username.type != FR_TYPE_STRING || (env_data->username.vb_length == 0)) {
                RWARN("\"%s\" is required for authentication", env_data->username_tmpl->name);
        error:
                smtp_slab_release(randle);
                RETURN_MODULE_INVALID;
        }
 
        if (env_data->password.type != FR_TYPE_STRING || (env_data->password.vb_length == 0)) {
                RWARN("\"%s\" is required for authentication", env_data->password_tmpl->name);
                goto error;
        }
 
        FR_CURL_REQUEST_SET_OPTION(CURLOPT_USERNAME, env_data->username.vb_strvalue);
        FR_CURL_REQUEST_SET_OPTION(CURLOPT_PASSWORD, env_data->password.vb_strvalue);
 
        if (fr_curl_io_request_enqueue(t->mhandle, request, randle)) RETURN_MODULE_INVALID;
 
        return unlang_module_yield(request, smtp_io_module_resume, smtp_io_module_signal, ~FR_SIGNAL_CANCEL, randle);
}
 
static int mod_instantiate(module_inst_ctx_t const *mctx)
{
        rlm_smtp_t                      *inst = talloc_get_type_abort(mctx->mi->data, rlm_smtp_t);
 
        inst->conn_config.reuse.num_children = 1;
        inst->conn_config.reuse.child_pool_size = sizeof(fr_mail_ctx_t);
 
        return 0;
}
 
#define SMTP_COMMON_CLEANUP \
        fr_mail_ctx_t   *mail_ctx = talloc_get_type_abort(randle->uctx, fr_mail_ctx_t); \
        if (mail_ctx->mime) curl_mime_free(mail_ctx->mime); \
        if (mail_ctx->header) curl_slist_free_all(mail_ctx->header); \
        if (mail_ctx->recipients) curl_slist_free_all(mail_ctx->recipients)
 
static int smtp_onetime_request_cleanup(fr_curl_io_request_t *randle, UNUSED void *uctx)
{
        SMTP_COMMON_CLEANUP;
 
        if (randle->candle) curl_easy_cleanup(randle->candle);
 
        return 0;
}
 
static int smtp_persist_request_cleanup(fr_curl_io_request_t *randle, UNUSED void *uctx)
{
        SMTP_COMMON_CLEANUP;
 
        if (randle->candle) curl_easy_reset(randle->candle);
 
        return 0;
}
 
static int smtp_onetime_conn_alloc(fr_curl_io_request_t *randle, UNUSED void *uctx)
{
        fr_mail_ctx_t           *mail_ctx = NULL;
 
        MEM(mail_ctx = talloc_zero(randle, fr_mail_ctx_t));
        randle->uctx = mail_ctx;
 
        smtp_slab_element_set_destructor(randle, smtp_onetime_request_cleanup, NULL);
 
        return 0;
}
 
static int smtp_mail_ctx_free(fr_mail_ctx_t *mail_ctx)
{
        if (mail_ctx->randle && mail_ctx->randle->candle) curl_easy_cleanup(mail_ctx->randle->candle);
 
        return 0;
}
 
static int smtp_persist_conn_alloc(fr_curl_io_request_t *randle, UNUSED void *uctx)
{
        fr_mail_ctx_t           *mail_ctx = NULL;
 
        MEM(mail_ctx = talloc_zero(randle, fr_mail_ctx_t));
        mail_ctx->randle = randle;
        randle->uctx = mail_ctx;
        randle->candle = curl_easy_init();
        if (unlikely(!randle->candle)) {
                fr_strerror_printf("Unable to initialise CURL handle");
                return -1;
        }
        talloc_set_destructor(mail_ctx, smtp_mail_ctx_free);
 
        smtp_slab_element_set_destructor(randle, smtp_persist_request_cleanup, NULL);
 
        return 0;
}
 
static inline int smtp_conn_common_init(fr_curl_io_request_t *randle, rlm_smtp_t const *inst)
{
#if CURL_AT_LEAST_VERSION(7,45,0)
        FR_CURL_SET_OPTION(CURLOPT_DEFAULT_PROTOCOL, "smtp");
#endif
        FR_CURL_SET_OPTION(CURLOPT_URL, inst->uri);
#if CURL_AT_LEAST_VERSION(7,85,0)
        FR_CURL_SET_OPTION(CURLOPT_PROTOCOLS_STR, "smtp,smtps");
#else
        FR_CURL_SET_OPTION(CURLOPT_PROTOCOLS, CURLPROTO_SMTP | CURLPROTO_SMTPS);
#endif
        FR_CURL_SET_OPTION(CURLOPT_CONNECTTIMEOUT_MS, fr_time_delta_to_msec(inst->timeout));
        FR_CURL_SET_OPTION(CURLOPT_TIMEOUT_MS, fr_time_delta_to_msec(inst->timeout));
 
        if (DEBUG_ENABLED3) FR_CURL_SET_OPTION(CURLOPT_VERBOSE, 1L);
 
        if (fr_curl_easy_tls_init(randle, &inst->tls) != 0) goto error;
 
        return 0;
error:
        return -1;
}
 
static int smtp_onetime_conn_init(fr_curl_io_request_t *randle, void *uctx)
{
        rlm_smtp_t const        *inst = talloc_get_type_abort(uctx, rlm_smtp_t);
        fr_mail_ctx_t           *mail_ctx = talloc_get_type_abort(randle->uctx, fr_mail_ctx_t);
 
        randle->candle = curl_easy_init();
        if (unlikely(!randle->candle)) {
                fr_strerror_printf("Unable to initialise CURL handle");
                return -1;
        }
 
        memset(mail_ctx, 0, sizeof(fr_mail_ctx_t));
 
        return smtp_conn_common_init(randle, inst);
}
 
 
static int smtp_persist_conn_init(fr_curl_io_request_t *randle, void *uctx)
{
        rlm_smtp_t const        *inst = talloc_get_type_abort(uctx, rlm_smtp_t);
        fr_mail_ctx_t           *mail_ctx = talloc_get_type_abort(randle->uctx, fr_mail_ctx_t);
 
        memset(mail_ctx, 0, sizeof(fr_mail_ctx_t));
 
        return smtp_conn_common_init(randle, inst);
}
 
/*
 *      Initialize a new thread with a curl instance
 */
static int mod_thread_instantiate(module_thread_inst_ctx_t const *mctx)
{
        rlm_smtp_t              *inst = talloc_get_type_abort(mctx->mi->data, rlm_smtp_t);
        rlm_smtp_thread_t       *t = talloc_get_type_abort(mctx->thread, rlm_smtp_thread_t);
        fr_curl_handle_t        *mhandle;
 
        if (!(t->slab_onetime = smtp_slab_list_alloc(t, mctx->el, &inst->conn_config.reuse,
                                                     smtp_onetime_conn_alloc, smtp_onetime_conn_init,
                                                     inst, false, false))) {
                ERROR("Connection handle pool instantiation failed");
                return -1;
        }
        if (!(t->slab_persist = smtp_slab_list_alloc(t, mctx->el, &inst->conn_config.reuse,
                                                     smtp_persist_conn_alloc, smtp_persist_conn_init,
                                                     inst, false, true))) {
                ERROR("Connection handle pool instantiation failed");
                return -1;
        }
 
        mhandle = fr_curl_io_init(t, mctx->el, false);
        if (!mhandle) return -1;
 
        t->mhandle = mhandle;
        return 0;
}
 
/*
 *      Close the thread and free the memory
 */
static int mod_thread_detach(module_thread_inst_ctx_t const *mctx)
{
        rlm_smtp_thread_t               *t = talloc_get_type_abort(mctx->thread, rlm_smtp_thread_t);
 
        talloc_free(t->mhandle);
        talloc_free(t->slab_persist);
        talloc_free(t->slab_onetime);
        return 0;
}
 
/** Parse the header section into tmpls for producing email headers
 *
 */
static int smtp_header_section_parse(TALLOC_CTX *ctx, call_env_parsed_head_t *out, tmpl_rules_t const *t_rules,
                                     CONF_ITEM *ci,
                                     UNUSED call_env_ctx_t const *cec, UNUSED call_env_parser_t const *rule)
{
        CONF_SECTION const      *cs = cf_item_to_section(ci);
        CONF_ITEM const         *item = NULL;
        CONF_PAIR const         *cp;
        call_env_parsed_t       *parsed_env;
        tmpl_t                  *parsed_tmpl;
        ssize_t                 slen;
 
        while ((item = cf_item_next(cs, item))) {
                char    *to_parse;
 
                if (!cf_item_is_pair(item)) {
                        cf_log_err(item, "Entry is not in \"header = value\" format");
                        return -1;
                }
                cp = cf_item_to_pair(item);
 
                MEM(parsed_env = call_env_parsed_add(ctx, out,
                                                     &(call_env_parser_t){ FR_CALL_ENV_OFFSET("header", FR_TYPE_STRING, CALL_ENV_FLAG_CONCAT, rlm_smtp_env_t, headers) }));
 
                /*
                 *      Turn the conf pair `attr = value` to email header format
                 */
                to_parse = talloc_asprintf(NULL, "%s: %s", cf_pair_attr(cp), cf_pair_value(cp));
 
                slen = tmpl_afrom_substr(parsed_env, &parsed_tmpl,
                                         &FR_SBUFF_IN(to_parse, talloc_array_length(to_parse) - 1),
                                         cf_pair_value_quote(cp), value_parse_rules_quoted[cf_pair_value_quote(cp)],
                                         t_rules);
                talloc_free(to_parse);
 
                if (slen <= 0) {
                        cf_canonicalize_error(cp, slen, "Failed parsing header", cf_pair_value(cp));
                error:
                        call_env_parsed_free(out, parsed_env);
                        return -1;
                }
 
                if (tmpl_needs_resolving(parsed_tmpl) &&
                    (tmpl_resolve(parsed_tmpl, &(tmpl_res_rules_t){ .dict_def = t_rules->attr.dict_def }) < 0)) {
                        cf_log_perr(cp, "Failed resolving header");
                        goto error;
                }
 
                call_env_parsed_set_tmpl(parsed_env, parsed_tmpl);
        }
 
        return 0;
}
 
static const call_env_method_t method_env = {
        FR_CALL_ENV_METHOD_OUT(rlm_smtp_env_t),
        .env = (call_env_parser_t[]) {
                { FR_CALL_ENV_PARSE_OFFSET("username", FR_TYPE_STRING, CALL_ENV_FLAG_NULLABLE | CALL_ENV_FLAG_CONCAT, rlm_smtp_env_t, username, username_tmpl),
                                          .pair.dflt_quote = T_DOUBLE_QUOTED_STRING },
                { FR_CALL_ENV_OFFSET("password", FR_TYPE_STRING, CALL_ENV_FLAG_NULLABLE | CALL_ENV_FLAG_CONCAT, rlm_smtp_env_t, password), .pair.dflt_quote = T_DOUBLE_QUOTED_STRING },
                { FR_CALL_ENV_OFFSET("sender_address", FR_TYPE_STRING, CALL_ENV_FLAG_NONE, rlm_smtp_env_t, sender_address) },
                { FR_CALL_ENV_OFFSET("recipients", FR_TYPE_STRING, CALL_ENV_FLAG_NULLABLE, rlm_smtp_env_t, recipient_addrs),
                                     .pair.dflt = "&SMTP-Recipients[*]", .pair.dflt_quote = T_BARE_WORD },
                { FR_CALL_ENV_OFFSET("TO", FR_TYPE_STRING, CALL_ENV_FLAG_NULLABLE, rlm_smtp_env_t, to_addrs),
                                    .pair.dflt = "&SMTP-TO[*]", .pair.dflt_quote = T_BARE_WORD },
                { FR_CALL_ENV_OFFSET("CC", FR_TYPE_STRING, CALL_ENV_FLAG_NULLABLE, rlm_smtp_env_t, cc_addrs),
                                    .pair.dflt = "&SMTP-CC[*]", .pair.dflt_quote = T_BARE_WORD },
                { FR_CALL_ENV_OFFSET("BCC", FR_TYPE_STRING, CALL_ENV_FLAG_NULLABLE, rlm_smtp_env_t, bcc_addrs),
                                    .pair.dflt = "&SMTP-BCC[*]", .pair.dflt_quote = T_BARE_WORD },
                { FR_CALL_ENV_OFFSET("attachments", FR_TYPE_STRING, CALL_ENV_FLAG_NULLABLE, rlm_smtp_env_t, attachments),
                                    .pair.dflt = "&SMTP-Attachments[*]", .pair.dflt_quote = T_BARE_WORD },
                { FR_CALL_ENV_SUBSECTION_FUNC("header", CF_IDENT_ANY, CALL_ENV_FLAG_SUBSECTION, smtp_header_section_parse) },
 
                CALL_ENV_TERMINATOR
        }
};
 
static const call_env_method_t auth_env = {
        FR_CALL_ENV_METHOD_OUT(rlm_smtp_auth_env_t),
        .env = (call_env_parser_t[]) {
                { FR_CALL_ENV_PARSE_OFFSET("username_attribute", FR_TYPE_STRING,
                                           CALL_ENV_FLAG_ATTRIBUTE | CALL_ENV_FLAG_REQUIRED | CALL_ENV_FLAG_CONCAT | CALL_ENV_FLAG_NULLABLE,
                                           rlm_smtp_auth_env_t, username, username_tmpl), .pair.dflt = "&User-Name", .pair.dflt_quote = T_BARE_WORD },
                { FR_CALL_ENV_PARSE_OFFSET("password_attribute", FR_TYPE_STRING,
                                           CALL_ENV_FLAG_ATTRIBUTE | CALL_ENV_FLAG_REQUIRED | CALL_ENV_FLAG_CONCAT | CALL_ENV_FLAG_NULLABLE | CALL_ENV_FLAG_SECRET,
                                           rlm_smtp_auth_env_t, password, password_tmpl), .pair.dflt = "&User-Password", .pair.dflt_quote = T_BARE_WORD },
                CALL_ENV_TERMINATOR
        }
};
 
/*
 *      The module name should be the only globally exported symbol.
 *      That is, everything else should be 'static'.
 *
 *      If the module needs to temporarily modify it's instantiation
 *      data, the type should be changed to MODULE_TYPE_THREAD_UNSAFE.
 *      The server will then take care of ensuring that the module
 *      is single-threaded.
 */
extern module_rlm_t rlm_smtp;
module_rlm_t rlm_smtp = {
        .common = {
                .magic                  = MODULE_MAGIC_INIT,
                .name                   = "smtp",
                .inst_size              = sizeof(rlm_smtp_t),
                .thread_inst_size       = sizeof(rlm_smtp_thread_t),
                .config                 = module_config,
                .instantiate            = mod_instantiate,
                .thread_instantiate     = mod_thread_instantiate,
                .thread_detach          = mod_thread_detach,
        },
        .method_group = {
                .bindings = (module_method_binding_t[]){
                        { .section = SECTION_NAME("authenticate", CF_IDENT_ANY), .method = mod_authenticate, .method_env = &auth_env },
                        { .section = SECTION_NAME("mail", CF_IDENT_ANY), .method = mod_mail, .method_env = &method_env },
 
                        MODULE_BINDING_TERMINATOR
                }
        }
};